1. Field of the Invention
Embodiments of the present invention relate, in general, to systems and method for wireless channel management and particularly to the fair usage of channels associated with a wireless network.
2. Relevant Background
Although broadband service has been available for some time, widespread access is still limited. In 2007 there were only 19.6 broadband subscribers per 100 inhabitants in the United States. While the United States ranked 15th in broadband access with respect to the number of inhabitants, the number of broadband subscribers is universally low when compared to the demand for broadband access.
The principle means by which broadband access is currently provided is either via cable or a Digital Subscriber Line (“DSL”). Both cable and DSL present significant barriers to the expansion of broadband access. For example, many are outside of the reach of DSL services. Cable service requires an extensive residential cable infrastructure and is not available to many residences. Lastly, a significant portion of those demanding broadband access feel that the cost of such access is prohibitive.
As an alternative to DSL or cable, the Institute of Electric and Electronics Engineers (“IEEE”) developed and promoted a wireless broadband standard. IEEE standard 802.16 defines the Wireless Metropolitan Area Network (“WirelessMAN”) air interface specification (also known as the IEEE WirelessMAN standard). This wireless broadband standard is new in comparison to the more mature standards such as 802.11 used for Wi-Fi networks commonly seen in homes and businesses. However, the 802.11 standard is primarily used for small local area networks while the 802.16 standard is designed to be used as a means of allowing wireless broadband access to a larger area as an alternative to cable and DSL connections.
The initial goal of 802.16 is to implement a set of broadband wireless access standards for WirelessMANs. To this end, much of the focus of 802.16 is on the “last mile” that would allow fixed and mobile wireless substations to connect to the fixed wireless base stations (“BSs”), thus allowing the delivery of high-speed Internet connections to the customer.
Because of its wireless nature, WirelessMAN can be faster to deploy, easier to scale, and more flexible, thereby giving it the potential to serve customers not served or satisfied by existing broadband services. WirelessMAN is similar to cellular systems in that it uses BSs that service a radius of several miles. The BS may be on a tower or reside on a tall building or elevated structure. The signal generated from these BSs is routed via standard Ethernet cable directly to a single computer, a hot spot or a wired Ethernet LAN. As will be recognized by one skilled in the relevant art, each BS can possess a transmitter and receiver of some form as well as a machine capable of executing instructions embodied as software. These software instructions can be stored on the BS in memory or conveyed to the BS via a wired link.
For the purposes of the present invention, consider the following definitions.
WirelessMAN-CX is the designation used to describe the realization that adds coordinated coexistence mechanisms to systems operating below 11 GHz in non-exclusively assigned or non-exclusively licensed bands.
WirelessHUMAN is the designation used to describe the realization that adds uncoordinated coexistence mechanisms to systems operating below 11 GHz in non-exclusively assigned or non-exclusively licensed bands.
Coexistence Signaling Interval (“CSI”) is a predefined time slot not associated with the CXCC (coexistence control channel), used for coexistence signaling purposes between systems which may have different physical layers (“PHYs”). This technique uses power keyed energy symbols and RSSI (receive signal strength indicator) detection, by a BS to contact its coexistence neighbor BS through one or more coexistence neighbor sub stations (“SSs”) in the common coverage area.
Operation Coexistence Signaling Interval (“OCSI”) includes all the CSIs other than signal intervals periodically reallocated to OBSs (operating base stations).
Initialization Coexistence Signaling Interval (“ICSI”) is the periodically appointed CSI specially used by an Initializing Base Station (“IBS”) to contact its neighbor OBS. When the IBS gets the OCSI allocation and starts the operating stage, it will cease from using the ICSI.
By positioning several BSs within a metropolitan area, users can move throughout the area without loss of signal. For example, a user may be connected to the Internet via an 802.11 hot spot at work and then, when undocked, use 802.16 while roaming the city or traveling to the suburbs. One portion of the 802.16 standard (802.16h) provides procedures and improved coexistence mechanisms for license-exempt operation.
These standards, however, fail to address what systems (also referred to herein as BSs and cells) working in a congested channel environment should do when channels are identified with fewer working systems than anticipated. Furthermore, 802.16h does not provide methods to avoid channel switching collisions nor can it guarantee fair channel usage when a system switches to a new working channel.
Consider the example shown in FIG. 1. FIG. 1 shows a configuration of 802.16h BSs with overlapping coverage, as would be known in the prior art. In this example, system 1 110, system 2 115, and system 3 120 operate on channel 1. System 4 125, system 5 130, system 6 135, and system 7 140 operate on channel two. Thus channel 1 is associated with three systems and channel 2 is associated with two instances of 2 systems. In this example three separate communities initially exist, community 1 150 comprising systems 6 and 7, community 2 160 comprising systems 1, 2 and 3, and community 3 170 comprising systems 4 and 5. Assume that system 5 130 ceases to operate or ceases to interfere with system 4 125. In that scenario channel 2 is, in the instance of community 3 170, associated with a single system, system 4 125 while neighboring system 3 120 in community 2 160 is using channel 1 and is associated with two other systems. The prior art fails to address this disparity in congestion within a working channel of neighboring systems and neighboring communities.